The present invention relates to electronic documents containing raster images.
PostScript is a resolution-independent format. Fonts can be enlarged or reduced in size to accommodate any viewing resolution. When a viewer zooms in or out of a document, the text characters automatically scale accordingly. Thus it can be said that font characters are xe2x80x9cscalable.xe2x80x9d
Similarly, graphical objects based on vector graphics consisting of line segments and curves are also scalable. The line segments and curves can be enlarged or reduced in size by appropriately modifying the pixel coordinates of their control points.
Raster graphics, on the other hand, is not scalable. An image expressed in raster graphics is by its nature pixel resolution specific, and to enlarge or reduce the image involves digital image filtering and interpolation. Moreover, a raster image cannot be stretched beyond its original pixel resolution without introducing artificial data.
The present invention provides an electronic document, including one or more raster images, which is scalable. The raster images are referenced within the document through dynamically changing references, and it is the control of the dynamic references that provides for the scalability. The scalable document of the present invention can be enlarged or reduced to any desired resolution, making the entire document scalablexe2x80x94text characters, graphical objects and raster images.
Regardless of the viewing configuration, a raster image referenced within the scalable document of the present invention will automatically scale according to the viewing resolution. For example, suppose a 6xe2x80x3xc3x978xe2x80x3photograph is converted to a high quality digital image by scanning at 600 dots per inch (dpi). This produces a 3,600xc3x974,800 pixel image, which is embedded into a page of the document.
When this page is viewed at normal size on a view monitor having 72 dpi resolution, the referenced image is scaled to 432xc3x97576 pixels for purposes of display. If a user zooms in by a factor of two, to see a portion of the page containing the image at higher resolution, the referenced image is scaled to 864xc3x971,152 pixels. Thus the dimensions of the image referenced within the document automatically scale to twice their original values. If the document is printed on a 300 dpi color printer, the referenced image is scaled to 1,800xc3x972,400 pixels in order to produce as high quality a print as possible using the color printer as an output device.
In a preferred embodiment of the present invention the referenced images are located on one or more image servers on the Internet or any other suitable computer network, and may be viewed on remote client computers. The raster images are not embedded within the scalable document, but rather are stored as separate files. The scalable document contains references to the raster images embedded therewithin, thus making the size of the scalable document relatively small. Upon display, the document will include screen-size images within it. Upon delivery or print, the document will include images scaled to the appropriate device resolution.
Each client computer preferably downloads only the portion of the image data that is necessary for satisfying a user display request, as described hereinbelow. Continuing with the example above, the 3,600xc3x974,800 image uncompressed occupies a total of 51.84 MB (at 3 bytes per pixel). High fidelity compression typically reduces this by an order of magnitude, to roughly 5 MB. Rather than requiring each client to download the entire 5 MB of image data, the present invention only requires the clients to download that portion of the image data necessary to satisfy the user display request. The user display request is significantly less than the entire image size, since the maximum size image that can be viewed on a video monitor is the full video monitor pixel resolution, which may be 768xc3x971,024 for example. Similarly when saving or printing the document, the user may specify a resolution less than 600 dpi for the save operation, or the printer resolution may be less than 600 dpi, in which case the client only needs to download a portion of the full image data
The present invention also provides a rendition tool for converting standard documents with large high quality images into scalable documents, and a delivery tool for converting scalable documents into standard documents. The rendition tool is used for creating Web-Ready documents with screen-size images for interactive viewing. The delivery tool is used for saving documents containing high quality images at user specified resolutions, and for printing such documents at resolutions appropriate to specified output devices.
There is thus provided in accordance with a preferred embodiment of the present invention a method for viewing a document containing at least one page and at least one image, the document being located on a server computer, including the steps of sending by a client computer a page display request to the server computer, creating by the server computer a layout page containing a reference to stored image data, transmitting the layout page from the server computer to the client computer, sending an image data request to a remote computer according to the reference to stored image data, and transmitting requested image data from the remote computer to the client computer in response to the image data request.
There is also provided in accordance with a preferred embodiment of the present invention a system for viewing a document containing at least one page and at least one image, the document being located on a server computer, including a client computer transmitter sending a page display request to the server computer and sending an image data request to a remote computer according to a reference to stored image data, a layout page producer within the server computer creating a layout page containing the reference to stored image data, a server computer transmitter transmitting the layout page to the client computer, and a remote computer transmitter transmitting requested image data to the client computer in response to the image data request.
There is also provided in accordance with a preferred embodiment of the present invention a scalable document including at least one layout page, and at least one reference to stored image data, the at least one reference including at least one command for processing the stored image data.
There is also provided in accordance with a preferred embodiment of the present invention a method for converting a document containing at least one image into a scalable document, including extracting at least one image from the document, storing the at least one image as stored image data, and replacing the at least one image by at least one reference to stored image data, the at least one reference containing at least one command for processing the stored image data.
There is also provided in accordance with a preferred embodiment of the present invention a system for converting a document containing at least one image into a scalable document, including an object extractor extracting at least one image from the document, a storage device for storing the at least one image as stored image data, and a reference inserter replacing the at least one image by at least one reference to the stored image data, the at least one reference containing at least one command for processing the stored image data.
There is also provided in accordance with a preferred embodiment of the present invention a method for converting a scalable document into a standard document using at least one reference to stored image data, the scalable document containing at least one layout page, and the at least one reference including at least one command for processing the stored image data, including processing the stored image data in accordance with the at least one command, producing at least one image, and positioning the at least one image within the scalable document according to positioning instructions within the layout page.
There is also provided in accordance with a preferred embodiment of the present invention a system for converting a scalable document into a standard document using at least one reference to stored image data, the scalable document containing at least one layout page, and the at least one reference including at least one command for processing the stored image data, including an image processor processing the stored image data in accordance with the at least one command, producing at least one image, and an image positioner positioning the at least one image within the scalable document according to positioning instructions within the layout page.